The subject matter disclosed herein relates to heating, ventilation and air conditioning (HVAC) systems. More specifically, the subject matter disclosed herein relates to evaporators for HVAC systems.
HVAC systems, such as chillers, use an evaporator to facilitate a thermal energy exchange between a refrigerant in the evaporator and a medium flowing in a number of evaporator tubes positioned in the evaporator. In a flooded evaporator, the tubes are submerged in a pool of refrigerant. This results in a particularly high volume of refrigerant necessary, depending on a quantity and size of evaporator tubes, for efficient system operation. Another type of evaporator used in chiller systems is a falling film evaporator. In a falling film evaporator, the evaporator tubes are positioned typically below a distribution manifold from which refrigerant is urged, forming a “falling film” on the evaporator tubes.
In one type of falling film evaporator, the distribution system includes a plurality of sprayers from which a vapor-liquid refrigerant mixture is sprayed directly onto the evaporator tubes, requiring complex and costly distribution systems and sprayer assemblies. In another, a separator is used to separate vapor refrigerant from liquid refrigerant, and the system relies on gravity working through a column of liquid refrigerant to drip the liquid refrigerant onto the evaporator tubes. This system requires the addition of the separator, and a considerable refrigerant charge to effect the gravity feed.